Method of making electric heating units



INVENTOR ATT.ORNEY Edda/f Bray.

Oct. 10, 1939. R. BREY METHOD OF MAKING ELECTRIC HEATING UNITS Filed April 15, 1938 WITNESSES: 2%

Patented Oct. 10, 1939 UNITED STATE METHOD OF MAKING ELECTRIC HEATING UNITS Rudolf Brey, Coswig, Germany, alaignor to Wcatinghouse Electric a Manufacturing Company, East Pittsburgh, Pa acorporation of Pennsylvania ApplicationmApril 15, 1938, Serial No. 202,248

Germany 2 Claims.

My invention relates to electric heating units and more particularly to range surface units and the method of making the same.

Electric cooking hot plates are now known to v the art in which a heating element is imbedded in insulating material between two cover plates of material capable of withstanding high heat. The cover sheets are provided with grooves which, for example, extend in the manner of a spiral or in back and forth windings, and are usually connected to each other by welding after the heating coil and its insulation are disposed therein. In hot plates of this type it is difllcult to make the filling grainy insulating material so dense that it will efllciently transfer the heat produced by the heating coil to the cover sheets.

It is, therefore, an object of my invention to provide a method of making a hot plate or heating unit in which, after the filling in of the insulating material within the grooves of a grooved cover plate and the rigid attachment or welding of a second cover sheet thereto, a further or additional special impression is utilized for the purpose of making the insulating material a dense solid homogeneous mass which will efficiently transfer the heat produced by the heating coil to the cover sheets.

A further object of my invention is to provide a range surface unit having an efllcient rugged compact heating unit which is formed from a plurality of cover sheets.

Other objects of my invention will either be pointed out specifically in the course of the following description of one form of system embodying my invention, or will be apparent from such description.

In the accompanying drawing:

Figure 1 is an exemplary embodiment of a range surface or cooking unit embodying my invention and illustrated in section, and

Figs. 2 to 7 illustrate the development and process of making the heating unit shown in Fig. l.

Referring to the accompanying figures, I show a range surface unit comprising in combination a supporting frame or casing l6 and a heating unit 6. The heating unit 6 includes grooved cover plates II and 20, insulating material 9 and I0 and a heating element l3.

The heating conductor or element 13, as shown in Figs. 4 to 7, inclusive, is imbedded in a grainy homogeneous insulating mass or material l5 between the groove ll of cover sheet H and the second cover sheet 20. The space below the cover aboetsor heating unit 6 is enclosed by the sheet April 20, 1931 metal housing or casing i6, and the conductors 19 which extend from plugs or terminals 22 of the surface unit 5 to the heating coils ii are insulated so that they shall not be subjected to the heat of the heating unit 6. If desired, an insulating buttress ll of ceramic material or a radiation plate ll,.or both, may be arranged between the heating unit 6 and the conductors iii to retard the downward radiation and conduction of the energy from such heating unit.

when making the heating unit 6, the upper grooved cover sheet II is inverted or positioned so that the groove l2 located therein extends directly downwardly. The groove I2 is then open at the top. Insulating material lll is then positioned within the groove I! so as to substantially flll it. A groove I4 is then pressed into the insulating material ID as such material is pressed or compressed in any desired manner, 'as shown in Fig. 3. The heating coil or element I3 is then inserted or positioned within groove H as shown in Fi 4.

The groove l4 and heating element l3 are then covered with additional insulating material 9. The additional material is placed over the insulating material Ill and coil i3 so as to extend above the surface of the cover sheet II. The

cover sheet II and insulating material 9 is thencovered with the second cover plate 20. The cover plate 20 has a shallow groove 2| therein. The cover plate 20, after being positioned over the insulating material 8 in such a manner that groove 2| cooperates or registers with groove I! to form an elongated passage, is rigidly connected to the cover plate H, preferably by welding as shown in Fig. 6.

The insulating mass i5 including insulating material 9 and I. which fllis the hollow space or elongated passage formed by grooves l2 and 2|, is then made considerably more dense by pressing down or flattening the groove 2|. The groove 2| in cover plate 20 is flattened by such subsequent application of pressure substantially norml to plate 20 as indicated by the arrows in Fig. 6. During this operation the cover plate 20 is pressed into substantially a smooth flat surface plate as shown (inverted) in Fig. 7.

Fig. 7 illustrates a completed heating unit- This is the preferred normal Various modifications may be made in the de- -vice embodying my invention without departing from the spirit and scope thereof, and I desire, therefore, that only such limitations shall be placed thereon as are imposed by the prior art and the appended claims.

I claim as my invention:

-1. The method of making a heating unit embodying a grooved cover plate which includes, placing insulating material within the groove of the cover plate, positioning a heating element'on the insulating material, placing additional insulating material within the grooves so as to cover 2. The method of making a range surface unit embodying a grooved cover plate which includes, placing insulating material within a downwardly extending groove of an inverted cover plate, positioning a heating element within the groove and on said insulating material, placing additional insulating material within the groove to cover the heating element and extend above the level of the cover plate, positioning a second plate upon the cover plate and, rigidly attaching it thereto, the second plate having a groove therein which will cooperate with the groove in the cover plate to form substantially an enclosed elongated passage, and applying pressure upon the second plate so as to flatten the grooves therein and compress the insulating materials into substantially a single solid homogeneous mass.

VRUDOLF BREY; 

